The gases collected at the spout of steelworks converters are at high temperature and dustladen. If they are collected without burning or with only partial burning of the carbon monoxide which they contain, they have a certain calorific value. Hence it may be interesting to recover them and then to employ them as fuel or as reducer gases.
After they have passed in succession through the collector hood, the cooling chimney, the saturator, the washer and the induced draught fan, these cooled but still hot gases are saturated with water vapor and contain water droplets.
After passing through the induced draught fan these gases may have two destinations:
either that of being exhausted to the atmosphere by way of a chimney ending in a flare in which the carbon monoxide is burnt to carbon dioxide;
or that of being directed towards a storage gasometer and a distribution network.
The direction of the gases sometimes towards the one and sometimes towards the other of these two routes, necessitates a special diversion device which ensures satisfactory safety of operation under conditions rendered difficult by the large flows of gas and by the nature of these gases which are still hot although cooled, still dustladen although they have been subjected to dust extraction, and which may be saturated with water vapor and contain water droplets.
Various types of such devices are already known. But they are in general bulky; their operation is slow and the load loss which they cause in the gas circuit is high.